MongoDB self join(aggregation) of collection with parent references

Question

Hello I have this collection, with parent references, I need to do self join on this collection, so that output will contain the children to maximum depth in one document and also get the output based on "Type" field.

{ 
    "DescId" : "1", 
    "Desc" : "Testing", 
    "ParentId" : "null", 
    "Order" : 1.0, 
    "Type" : "A", 
    "Parent" : null
}

{ 
    "DescId" : "1.1", 
    "Desc" : "Testing Child 1", 
    "ParentId" : "1", 
    "Order" : 1.0, 
    "Type" : "B", 
    "Parent" : "Testing"
}

{ 
    "DescId" : "1.2", 
    "Desc" : "Testing Child 2", 
    "ParentId" : "1", 
    "Order" : 2.0, 
    "Type" : "B", 
    "Parent" : "Testing"
}

{ 

    "DescId" : "1.1.1", 
    "Desc" : "Testing grand child 1", 
    "ParentId" : "1.1", 
    "Order" : 1.0, 
    "Type" : "C", 
    "Parent" : "Testing Child 1"
}

At present I have this output based on answer given to my previous question:

{ 
    "ADescId" : "1", 
    "ADesc" : "Testing"
}
{ 
    "BDescId" : "1.1", 
    "BDesc" : "Testing child 1"
}
{ 
    "BDescId" : "1.2", 
    "BDesc" : "Testing Child 2"
}
{ 
    "CDescId" : "1.1.1", 
    "CDesc" : "Testing grandchild 1"
}

I have tried doing $graphlookup aggregation on this collection, somehow data seems to get messed up. Please let me know if there is a way to achieve this. Thanks.

Desired output:

{ 
    "ADescId" : "1", 
    "ADesc" : "Testing",
    "BDescId" : "1.1", 
    "BDesc" : "Testing child 1",
    "CDescId" : "1.1.1", 
    "CDesc" : "Testing grandchild 1"
}
{ 
    "ADescId" : "1", 
    "ADesc" : "Testing",
    "BDescId" : "1.2", 
    "BDesc" : "Testing Child 2"
}

If you need joins you're after a relational database, not nosql database in the first place mate. — Mike Doe, Jul 25 '18 at 09:14
Well then, I will have to rephrase my question. I am looking at aggregation of documents in the collection I have. — Vani Kulkarni, Jul 25 '18 at 09:20
I didn't mean the title. You're using wrong tools for the job, just saying. — Mike Doe, Jul 25 '18 at 09:25
I understood, but cannot help. Its part of application I am working on. — Vani Kulkarni, Jul 25 '18 at 09:32
Do you have a limit on the number of nestings that are present in the documents? Like apart from A,B,C levels.. — Subhashree Pradhan, Jul 25 '18 at 10:34
@VaniKulkarni how about 1.1.2 ? Do you expect to have one document per B level or cases like `1.1.1` and `1.1.2` should be displayed separately ? — mickl, Jul 25 '18 at 21:23
@mickl: Yes it should be separate, like this :`{ "ADescId" : "1", "ADesc" : "Testing", "BDescId" : "1.1", "BDesc" : "Testing child 1", "CDescId" : "1.1.2", "CDesc" : "Testing grandchild 2" }` — Vani Kulkarni, Jul 26 '18 at 04:57
@VaniKulkarni IMO technically that might be possible but that aggregation pipeline will be too complex. Maybe you can use `$graphLookup` to get parent with it's children and then process that in application layer — mickl, Jul 26 '18 at 06:12
@mickl: Ok,let me try to process it in application itself. Thank you. — Vani Kulkarni, Jul 26 '18 at 06:17

MongoDB self join(aggregation) of collection with parent references

0 Answers0